With fast development of network technologies, the Internet access technology is evolving. The home access mode is a new access mode currently being researched by the 3rd Generation Partnership Project (3GPP) and non-3GPP standardization organizations.
In home access mode, a User Equipment (UE) accesses a mobile network through a universal Internet Protocol (IP) access network by using a home Wireless Access Point (WAP) and the licensed spectrum. The licensed spectrum may be the spectrum used in various networks, for example, the UMTS Terrestrial Radio Access Network (UTRAN), Evolved UTRAN (E-UTRAN), Code Division Multiple Access (CDMA) network, Worldwide Interoperability for Microwave Access (WiMAX) network, Wireless Local Area Network (WLAN), and High Rate Packet Data (HRPD) network. A home WAP is also known as a Femtocell.
A Closed Subscriber Group (CSG) mechanism is introduced to restrict the access of a UE to a specific home WAP. The CSG identifies some UEs (or users) authorized to access one or more cells of an operator, but restricts the access of other UEs to such cells. A CSG area includes one or more cells, which are identified by a CSG Identifier (ID). A CSG area is accessible to a group of UEs, but not accessible to other UEs than this group of UEs. The CSG IDs of all CSG areas accessible to a UE form an Allowed CSG List, which is also known as a CSG White List. The Allowed CSG List of the UE is stored in a mobility management Network Element (NE) such as a Serving GPRS Support Node (SGSN) and a Mobility Management Entity (MME), or stored in a non-3GPP Gateway (GW) or the UE.
Currently, the 3GPP standardization organization is developing an Emergency Call (EMC) service in an IP Multimedia Subsystem (IMS) to provide emergency call services such as policy emergency calls and fire emergency calls for users by using an IP-Connectivity Access Network (IP-CAN) network (such as GPRS/UMTS/E-UTRAN/WLAN/WiMAX) and the IMS system.
However, the prior art has drawbacks. For example, when a UE is handed over from a source access NE to a target access NE or a target cell, no access control is exercised; and the access control is exercised only after the UE is handed over to the target access NE or target cell. In this mechanism, the access control is exercised only after the UE is handed over to the target access NE or target cell, and consequently, the UE is not allowed to access the target access NE or target cell after the handover, and the ongoing service on the UE is terminated, which impairs the user experience.
In the CSG mechanism, when the UE is handed over from the source home WAP to the target home WAP, if the CSG ID corresponding to the target home WAP does not exist in the Allowed CSG List of the UE, the access of the UE to the target home WAP is rejected; if the UE has an EMC service at this time, the EMC service is interrupted. The prior art provides no mechanism for processing the EMC service in this circumstance.